1. Field of the Invention
The present invention relates generally to hand-held sensors, such as for sensing objects of varying density in or adjacent walls, and in particular to a sensor with improved handling, display, and actuation.
2. Description of Related Art
Hand-held sensors are generally well known, such as disclosed in U.S. Pat. Nos. 4,099,118 and 4,464,622, which are incorporated herein by reference. These sensors measure the change in capacitance sensed by the a sensor circuitry as the sensor is moved across a wall. Typically, the capacitance varies due to studs, metal objects, pipes or other structural differences such as electrical wiring. The sensors generally display, such as with one or more light emitting diodes (LED's) the presence of such a change in capacitance indicating the presence of a stud or other object. The circuitry can detect and indicate the presence of an alternating current (AC) source in or behind the wall.
The exterior cases of the hand-held sensors generally are formed from a hard thermoplastic material, which can include various types of ridges or other similar raised gripping surfaces. Nonetheless, such cases inherently are slippery and can become more slippery due to moisture, such as due to the user's perspiration or rain. Further, unlike most hand tools which are held in a single manner and position during utilization, the hand-held sensors are held in a multitude of positions at many different angles, such as for scanning ceilings or walls above or below a user's height.
The sensors include one or a plurality of LED's to indicate the sensed change in capacitance or for other functions, such as calibration and/or AC source sensing. The LED's generally are arranged in a vertical or horizontal row across the sensor case, although one display, model number EZ380B, made by National in Japan includes a somewhat arrow shaped orientation of LED's. These LED displays are either covered by a transparent cover, such as in the National display, or are exposed and can protrude beyond the casing wall of the sensor, such as the vertical aligned LED display in a sensor sold under the name "Intellisensor Stud Sensor" made by The Stanley Works in New Britain, Connecticut. The exposed LED's or transparent covers can be scratched, damaged or broken when being stored or transported, or if dropped.
The actuators, especially when designed as slide actuators, can be of a complicated design and can bear against the switch mechanism or the circuitry and can cause defects in the sensor. The actuators often are glued or adhered to the switch mechanism and hence are subject to breakage.
It would be desirable to provide a hand-held sensor which is easily gripped, does not have exposed LED's and has an actuator which is easily manufactured, not subject to breakage and does not load the switch mechanism or circuitry.